JSON Prompt Builder — Visual API Message Constructor

Visually build OpenAI and Anthropic API message arrays. Copy JSON or cURL. Supports variables.

Variables

JSON Output

{
  "model": "gpt-4o",
  "messages": [
    {
      "role": "system",
      "content": "You are a helpful assistant."
    },
    {
      "role": "user",
      "content": "Hello, {{topic}}"
    }
  ]
}

cURL Command

curl https://api.openai.com/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -d '{
  "model": "gpt-4o",
  "messages": [
    {
      "role": "system",
      "content": "You are a helpful assistant."
    },
    {
      "role": "user",
      "content": "Hello, {{topic}}"
    }
  ]
}'

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Frequently Asked Questions

How do I use JSON Prompt Builder?

Build structured JSON prompts visually by adding fields, setting values, and previewing the formatted prompt in real time.

Is JSON Prompt Builder free?

Yes, JSON Prompt Builder on ToolPix is 100% free with no signup or installation required.

Is my data safe?

All processing happens in your browser, your data never leaves your device.

Who is JSON Prompt Builder designed for?

Developers, content creators, and anyone working with AI tools who wants to get better results faster.

Can I save my work?

Results can be copied to clipboard with one click. Browser local storage keeps your recent sessions.

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